Foil sensors are composed of a thin metal foil bonded to an insulating substrate, and are used in monitoring the structural health of high value structures.
However, existing sensors are manufactured by techniques that in each case are suitable for only a small range of foil materials. Consequently, such foils are not generally made of the parent structural material to be monitored; the corrosion detected by the sensor must therefore be related by some means to the corrosion on the parent structure. This may be described as an indirect monitoring approach; it can produce errors and it restricts the use of existing sensors to structures where the sensor/structure relationship is known.
Further, existing small structure manufacturing techniques used in the manufacture of sensors means that only a limited number of materials can be used in sensor manufacture, so the breadth of existing sensor types is small. These existing techniques also have difficulty producing thin foils and adhering thin foils to rigid insulating backings.